Posts tagged ‘invasive plants’

When one walks among a forest of native plants, plants who have lived together for hundreds or thousands of years, there is an obvious feeling of harmony that is different from what one feels when walking among a forest covered with honeysuckle, kudzu, multiflora rose, Japanese knotweed and privet. In the forest of ancient harmony, it appears plants are each given their respectful place of existence, room to grow and breed unimpeded by aggressive competition from other plant species. The healthy balance of this forest isn’t based on the behavior of what is above, but actually, the health depends on what lies below the surface: the relatively undisturbed soil and hidden mycelium of the forest Fungi Kingdom.

The Fungi Kingdom is perhaps the oldest group of living species, which made the earth inhabitable for plants. Fungi consist of the visible fruiting bodies called mushrooms, and the threadlike mycelium network underground and throughout decomposing matter, such as fallen trees. According to mycologist Paul Stamets, roughly eight miles of mycelium is living in one cubic inch of ground. Stamets also describes underground mycelium’s neurological network like the Internet, constantly giving and receiving information. Mycelium know when we are treading on them.

Fungi, unlike plants, contain no chlorophyll, though they do use radiation-as plants use light-to convert elements into food, and their byproducts during this conversion are what makes soil by which plants can live. Rotting mushrooms feed microbes, which in turn feed the forest. The relationship of symbiosis is very important when it comes to the Fungi and the Plant Kingdom. Many native plants depend on particular mycelium species in the soil in order to live, making them difficult to transplant or propagate, and thus threatening their population status.

The symbiotic relationship makes plants sensitive to habitat destruction from farming or prior farming and development-roads, subdivisions, strip-malls, cities. Once the soil habitat for particular mycelium is disturbed, the native plants living in the symbiotic relationship will struggle to live. Plants who are not sensitive to particular mycelium species, and perhaps attracted to nitrogen-depleted soil are opportunistic, and easily become invasive when the healthy balance is disturbed.

Other opportunistic species are viruses and microbes. In our gut is approximately three-five pounds of bacteria, which provide a foundation for our immune system. A disturbance in the friendly bacterium’s habitat can allow opportunistic pathogens to thrive. As Louis Pasteur, father of the germ theory, exclaimed in epiphany, “It’s the milieu!” Germs, microbes, pathogens take advantage of a weakness in the environmental system and proliferate. This is a similar pattern of behavior in invasive plants.

When we see invasive plants, we are seeing a symptom of ecological disturbance, not the cause of ecological disturbance. The total ecology, or relationship of organisms and elements, is far-far-far more complex than people understand. It is not as simple as pulling out privet and planting native species, as if that would perpetually remain a native-only plant place.

To rid the area, no matter how small or large, of invasive plants would require toxic herbicides, causing further ecological distress, or an introduction of a predatory species– which I assert is always a short-sighted and regretful idea–and constant vigilance in tending the “natural” native garden. Birds, animal fur, clothing and wind will continue to disperse seeds, making the maintenance of a native-only plant place a constant, resource-draining effort. And underlying the whole attempt, literally, for the survival of the native plants is the necessary re-establishment of the symbiotic mycelium.

A cost-benefit analysis would help here. We need to recognize some of the phytoremediation benefits of non-native, invasive species, such as with mimosa as a nitrogen-fixer, or purslane as an absorber of PCBs, or lamb’s quarters as a re-vegetation plant for mining sites and absorber of organophosphates. Furthermore, once invasives become the predominant species, they are performing the ecological benefits of erosion control, holding up our creek banks, and converting CO2 from our atmosphere into oxygen.

My Athens Banner-Herald column has received some criticism when I write of the virtues of an exotic, or a non-native, invasive species, for instance, with mimosa and purslane. One of my graduate school teachers, the eminent Dr. Jim Duke, retired from the USDA, and author of nearly 100 books on medicinal, economic and agricultural plants, as well as ethnobotany, and who developed and maintains the valued Phytochemical and Ethnobotanical Database, definitely doesn’t think that the U.S. should plant more kudzu, but he does recommend that we utilize the kudzu for biodiesel, food, phytoestrogen isoflavones-important for women during menopause, and as a medicinal aid for alcoholism. We should not pollute our water through the massive, and expensive, application of herbicides, trying to eradicate kudzu, or introduce a pest which has unintended consequences.

We need to utilize the plants growing abundantly around us, and to do that, we need to know what their benefits are. Through the gained knowledge from research of invasive species, we can learn how they are medicinal substitutes for threatened native medicinal plants, for example Japanese barberry (Berberis thunbergii) is a medicinal substitute for the threatened goldenseal (Hydrastis canadensis). To me that sounds like sustainable practices of plant harvesting, and sustainable stewardship.

Finally, the term “native” is quite arbitrary. Humans have been trading plants since we were able. Plants provide life-saving medicine, and have inspired seed swaps and spurred the global marketplace; the need for healing bridged the divide of differences. For example, in the 8-9th century, Emperor Charlemagne developed relations with Arab Muslims, who were more medically advanced than the Roman Empire, and instructed his officers to collect medicinal plants to bring back to Christian monasteries where they were grown in physic healing gardens. Comfrey (Symphytum officinale) is one of those plants. In fact, it’s a custom in the old world of the Middle East to travel with a plant. Furthermore, if one looks specifically at the pre-Columbian history of America, one will see the trade of plants from east to west, north to south. Some of these plants naturalize in their new environment, essentially “going native”, and can become included in human botanical texts of native species.

Almost all plants are designed to disperse their seeds or spores through various mechanisms. It’s the compensation for being rooted to a place, the way to travel and increase one’s progeny. In untended circumstances where the human is not the gardener, the seed grows where it can.

Within a paradigm of a whole webbed universe, as in Cherokee stories, it might be said that the seed goes where it is called. For instance, poison ivy, a North American native, could be considered “invasive” today because it isn’t a desirable plant to most humans, and, being spread by birds who eat the berries, it shows up all over the eastern U.S. In Cherokee stories of natural history, there are 7 tribes of plants. One of those tribes is the warrior tribe who protects other vulnerable plant tribes from animal predators, or helps restore an area from disturbance. Poison ivy is the chief of the warrior tribe. Blackberries and smilax are also native American plants in the warrior tribe. In this perspective, poison ivy is doing its job, trying to keep humans away from more vulnerable plants, or helping a disturbed area to heal, which is why it’s so prolific in the eastern United States. Next time you see poison ivy growing, notice where you are. What disturbances have taken place? What plants might the ivy be protecting from you?

Pay attention to the plants that begin to reclaim an area that’s been developed. My mind goes to the old houses on secondary roads covered in kudzu, or the weeds coming up through the sidewalk cracks. These are called invasive, but they also demonstrate how awesome is nature’s power of reclamation and, hopefully, restoration.

To learn more about the importance of mycelium, watch Paul Stamets at the 2008 TED Conference on the vodpod video in the right sidebar.